This hash was locally crafted and pressed using a modern take on traditional hash-making techniques, it was created through a process that is entirely mechanical, without the use of any butane or any other solvents to extract the cannabinoids and terpenes from the cannabis plant.
Bubble hash is a term given to hash made from pure trichomes. When you fire up traditional hashish, impurities in the resin will burn. Pure, unadulterated cannabis-trichome resin will bubble and melt like butter when flame is applied.
The basic principle is this: plant material (either dry or fresh-frozen generally) is mixed with cold water and ice, then agitated manually or mechanically in order to break off the now-brittle trichome heads. This solution is then filtered through specifically-sized screens to remove anything undesirable, leaving behind a relatively pure finished product.